The invention disclosed and claimed herein generally pertains to the field of coupling devices of the type which may be rapidly attached to a structure by means of a few, simple motions. More particularly, the invention pertains to the field of devices of the above type which are employed to couple substantial forces to a plate-like structure, i.e. a structure having a thickness which is small in relation to its surface area. Even more particularly, the invention pertains to coupling devices of the above type, wherein a device is attached by means of a single linear movement, which thrusts the device into and through a circular hole through the structure, and a subsequent rotational movement of less than a complete revolution to prevent the device from being pulled back through the hole, even when a substantial force is applied to the device.
There is increasing interest in the use of remotely controlled underwater work systems for performing a variety of mechanical tasks in an underwater environment. In an important class of such tasks, for example, in underwater salvage operations, it is necessary to attach cables or other structure to underwater objects to impart substantial forces thereto. In such operations, the viewability of a work site, through an underwater TV camera, as well as control of tools located at the site, may be very limited for a remotely located operator. Consequently, it is extremely important that the task of attaching a lifting cable to an underwater object be performed with as few discrete mechanical operations as possible.
In addition to the above requirement, it is very likely in underwater salvage that it will be necessary to attach a lifting cable to a plate or panel-like structure wherein only one side of the structure is accessible.
To recover an object such as a sunken craft which has no component to which a lifting cable may be readily attached, it has generally been necessary to use slings, grapples or nets, techniques which tend to be very cumbersome, slow and frequently ineffective. It has been considered that a remotely controlled work system could be employed to bore circular holes through plate-like components of an object to be salvaged, and then insert coupling devices therethrough of the type which may be secured to a plate by performing tasks on only one side of the plate. However, conventional devices of such type, such as toggle bolts, have been found to be unacceptable for supporting weight which may be on the order of several thousand pounds. Alternatively, such devices may not be deployable in a plate-like structure without the performance of fairly complicated operations, such as perforating the structure with holes of non-circular cross-section, or may require that holes of unacceptably large diameter be drilled through the structure.
In the present invention, a coupling device is provided which may be employed to rapidly attach a lifting cable or other structure to a plate of selected thickness by means of a very limited number of simple mechanical operations. To attach the device it is only necessary to drill a circular hole through the plate, apply a single linear movement to the device to insert it through the hole, and apply a single rotational movement to the device to prevent its being pulled back through the hole, even when substantial force is applied thereto. The diameter of the hole which must be drilled is comparatively small in relation to a shaft which traverses the hole and which carries the force therethrough, to apply it to the far side of the plate. An embodiment of the device is generally recoverable and reuseable, and it is anticipated that the invention will be useful in a wide range of situations, wherever it is important to rapidly join a coupling device to a plate-like structure, or to join a coupling device to a plate-like structure having only one accessible side.